Imagewise exposed gelatino silver halide emulsion treated with pyruvic aldehyde hardener

ABSTRACT

A PROCESS FOR THE HARDENING TREATMENT OF A SILVER HALIDE PHOTOGRAPHIC MATERIAL COMPRISING TREATING THE SILVER HALIDE PHOTOGRAPHIC MATERIAL WITH PYRUVIC ALDEHYDE DURING A PHOTOGRAPHIC PROCESSING STEP IS DISCLOSED.

United States Patent US. Cl. 96-50 11 Claims ABSTRACT OF THE DISCLOSURE A process for the hardening treatment of a silver halide photographic material comprising treating the silver halide photographic material with pyruvic aldehyde during a photographic processing step is disclosed.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention relates to a process for the hardening treatment of photographic light-sensitive materials. More particularly, this invention relates to a method of hardening the emulsion layer of a gelatino-silver halide photographic material during the processing step thereof.

(2) Description of the prior art Rapid treatment of a photographic light-sensitive material (rapid developing and image preparing) is generally carried out by raising the temperature thereby increasing the reaction speed. Moreover, reversal color photographic materials require complicated processings for a long period of time, for example, color developing after first developing (black and white), stopping, fixing, bleaching and water washing.

In using a high temperature treatment or a long time treatment as in such an example, a gelatin emulsion layer possesses the disadvantages in that the physical strength decreases, crepe-like lines described as reticulation occur on the surface of the gelatin layer and the drying load increases.

As a method for preventing this problem, a large amount of a hardener is previously incorporated in an emulsion layer during the preparation of the photographic light-sensitive material so as to give the physical strength suilicient to resist the severe processing conditions. In this case, however, there are some disadvantages in that a phenomenon, which is called after hardening, occurs with the physical strength of emulsion layer varying gradually during storage of the photographic light-sensitive material, resulting in retention of photographic quality being difiicult, permeation or diffusion of the developer being hindered, resulting in a reduction in the apparent sensitivity, since the emulsion layer is hardened excessively to increase the physical strength.

Another method has thus been proposed wherein a photographic light-sensitive material is hardened during development in place of hardening excessively during preparation of the material, for example, hardening development with diglycol aldehyde (as disclosed in British Patent No. 1,113,342), hardening development with 2,3- dihydroxy-l,4dioxane (as disclosed in US. Pat. No. 3,380,829) and prehardening with an aliphatic dialdehyde (as disclosed in British Pat. No. 825,544).

The desired conditions for such a hardener are as follows:

(1) Hardening is effectively carried out Without causing any chemical fog with a photographic emulsion. (Al- Patented Oct. 3, 1972 dehydes tend to cause fog with silver halide emulsions due to their reducing property.)

(2) The hardening reaction takes place rapidly and in a short processing time in an eilective manner.

(3) Only a small amount of hardener is sufiicient.

(4) No interaction with color formers, for which the interaction cause a turbidity in color.

There have been no or almost no ideal hardeners satistying the above-described conditions. Many of the known hardeners are accompanied by disadvantages such as giving an unfavorable fog to photographic emulsions, causing interaction with color formers and showing no rapid elfectiveness.

It is a principal object of this invention to provide a strong hardener available for color photographic lightsensitive materials and black and white photographic light-sensitive materials, whereby the above-described disadvantages are overcome.

SUMMARY OF THE INVENTION We the inventors have found the objects of this invention can be accomplished using pyruvic aldehyde (monomethyl glyoxal). The process of this invention comprises a hardening treatment of a silver halide photographic material using pyruvic aldehyde during the photographic processing step of the photographic material. Where this compound is previously added to a gelatin emulsion and coated, its hardening property is not sulficient. In addition, a reducing fog is generated in the emulsion. Accordingly, this unfavorably compares in practical use with recently developed hardeners for emulsion additives, having excellent hardening effects as well as photographic elfects. When the pyruvic acid is used as a hardener for the prehardening treatment, however, the hardening reaction is rapidly carried out with less adverse influence on the photographic properties of the silver halide, such as fogging action, and without interaction with color formers.

The concentration of the pyruvic aldehyde used in a prehardening bath is from about 1 g./liter to 50 g./liter, although this will dilfer with the types of the photographic light-sensitive material, the composition of the prehardening bath and the subsequent processings.

The prehardening solution can further contain sodium sulfate, hard water softening agents, potassium bromide or other fog inhibitors and buffering salts. The pH of the solution can be varied within a considerably broad range of 3 to 12, preferably from 4 to 11, but a pH of about 4.8 is most preferred from the standpoint of the photographic characteristics and the strength of the emulsion layer.

Various inorganic salts are generally used in prehardener solutions in order to keep the ionic strength to a sufficiently high level and thereby prevent excessive swelling. Such inorganic salts are well known in the art. Some of the typically well known inorganic salts used for this purpose are alkali metal sulfates, magnesium sulfate, alkali metal borates, and alkali metal phosphates.

Formaldehyde can be used jointly in the prehardening bath as a second hardener, thereby increasing the hardening effect in an amount greater than the combination of the efiects of each used alone. In this case, from 5 to 30 ml. of a 37% aqueous solution of formaldehyde is added per 1,000 ml. of the prehardening solution in addition to the pyruvic aldehyde within the abovedescribed range.

As another method of advantageously using pyruvic aldehyde to obtain excellent hardening properties, an emulsion layer can be hardened while carrying out development by adding this hardener to a developing solution. In this case, the optimum concentration of the hardener, depending on the composition of the developing solution, and in particular, on the concentration of the sulfite ion, approximately ranges from 1 to 20 g./liter. When the hardener is added to a developer in the case of a color photographic light-sensitive material also, not only is the gelatin emulsion layer strongly hardened, but also little fog occurs and little unfavorable interaction with color formers take place, as in using in a prehardening solution.

The prehardener composition typically comprises from to 40 ml./l. of a 30% solution of pyruvic aldehyde, from 5 to 40 m1./l. of a 37% solution of formaldehyde, an inorganic salt to increase the ionic strength to greater than 1, and an acid or alkali to control the pH to from 4 to 11. A typical inorganic salt used is sodium sulfate in an amount of from 50 to 200 g./l.

The silver halide photographic emulsion to be adapted to the method of the invention is a dispersion of silver chloride, silver iodide, silver bromide, silver chlorobromide, silver iodobromide or silver chloroiodobromide in a protective colloid such as gelatin.

Since the process of the invention is characterized by using pyruvic aldehyde alone or in combination with formaldehyde, the developing agents and others are not limited and ones conventional can be used (see US. Pat. 3,380,829, British Pats. 825,544 and 1,113,342).

The following examples are given in order to illustrate the invention further in greater detail without limiting the scope of the invention.

EXAMPLE 1 A high speed negative light-sensitive material comprising a cellulose triacetate film base and gelatino-silver iodobromide emulsion layer coated thereon was exposed and then subjected to the following processing steps.

Tem era- Time Processing ture 0.) (minutes) Hardening bath 30 1 Water wa h 30 4 Development. 30 4 Water washing 30 0. 5 Fixin 30 1 Water washing 30 1. 5

The above-described hardening bath had the following composition:

Sulfuric acid (1:1) 5.4 ml.

Sodium sulfate 150 g.

Sodium acetate 20 g.

Hardener As shown in Table 1.

TABLE 1 Amount Milli- Fog Hardener used liters Grams density No agent 0.32 30% aqueous pyruvic aldehyde solution 0.32 25% aqueous glutaraldehyde solution- 0.75 2, 3-dihydroxy-1, 4-dioxane 5 0. 40 N o hardening bath 0. 30

The photographic film subjected to the foregoing hardening processing was then warmed in a 0.2 N sodium hydroxide solution and the temperatures at which the emulsion layer began to break down (which will hereinafter be referred to as the reticulation point of emulsion layer) and at which the emulsion layer began to melt in the solution (which will hereinafter be referred to as the melting point of the emulsion layer) were measured to obtain the following results.

Reticulation Melting point of point of emulsion emulsion layer layer Hardener used 0.) C.)

No agent 43. 0 45.0 Pyruvic aldehyde 49. 5 57.0 Glutaraldehyde 49. 0 56. 5 2, 3-dihydroxy-1,4-dioxane 45. 0 48. 0

Tem era- Time Processing ture 0.) (minutes) Water washing... 30 0. 5 Reversal exposure.

Second development" 30 4 Water washing..- 30 1 Bleaching. 3O 1 Water washin 0. 5

Fixing 30 1 Water washlng 30 1 1 Uniform exposure of 8,0001uxes on the emulsion surface for 1 second.

The composition of the hardening bath was the same as that used in Example 1.

Composition of the first developer N-methylparaaminophenol sulfate g-.. 2.0 Sodium sulfite g 90.0 Hydroquinone g 8.0 Sodium carbonate (monohydrate) g 52.5 Potassium bromide g 5.0 Potassium thiocyanate g 1.0 Water to make 1,000 ml.

Composition of the second developer Benzyl alcohol ml..- 5 .0 Sodium sulfite g 5.0 Hydroxylamine hydrochloride g 2.0 3-methyl-4-amino-N-ethyl-N-methanesulfonamideethylaniline sulfate g 1.5 Potassium bromide g 1.0 Trisodium phosphate g 30 Sodium hydroxide g 0.5 Ethylenediamine (70% aqueous solution) ml..- 7 Water to make 1,000 ml.

Composition of the bleaching solution Red prussiate g Sodium acetate g 40 Glacial acetic acid ml-.. 20 Potassium bromide g 30 Water to make 1,000 ml.

Composition of the fixing solution of pyruvic aldehyde. This confirms that pyruvic aldehyde does not give fog to photographic emulsions and has no unfavorable interaction with color formers, while many of the aldehydes described for comparison have disadvantages with respect to both of these points. Furthermore, a clear eifect is found also on the physical strength of the emulsion film toward which the present invention is directed, as shown in the table below.

A positive photographic light-sensitive material comprising a gelatino-silver chloroiodobromide emulsion was exposed and then subjected to the following processings:

'lem ere- Time Processing ture 0.) (minutes) See the following table.

Grams of- Composition of the Developer A B N-methyl-p-aminophenol sulfate 4. 5 4. 5 Sodium sulfite 15 15 Hydroquinone 8. 8. 0 Sodium carbonate (monohydrate) 41 41 Potassium bromide. 3. 3. 0 6-nitrob enzimidazole. 0 0. 1

30% aqueous pyruvic aldehyde solu mi er 10 Anthraquinonesulfonic aoid- 0. Sodium hydroxide 0. 1 Sodium sulfate 40 40 Water to make, ml 1, 000 1, 000

As the fixing solution an acidic hardening and fixing solution was used. There are no marked differences in the photographic properties between the developers, A and B, pyruvic aldehyde having no adverse influence on the photographic characteristics. The following differences in the physical strengths were determined.

A gelatino-silver halide photographic light-sensitive material for the positive, described in Example 3, was exposed and then subjected to the following processings:

Tern era- Time Processing ture 0.) (minutes) Hardenin 30 1 Water washing 30 1 Development. 30 4 Wate r washing... 30 0. 5 Fixing 30 1 Water washing 30 1. 5

See the following table.

Composition of the hardener C D E F Sulfuric acid (1:1), ml 5. 4 5. 4 5. 4 5. 4 Sodium sulfate, g 150 150 150 160 Sodium acetate, g 20 20 20 20 Pyruvic aldehyde (30%), ml 20 20 Formallu (37%), ml 10 Water was added thereto to make 1,000 ml. The pH at that time was 4.8. As the developer was used a conventional developer for positive photographic material comprising metol-hydroquinone and as the fixing solution, conventional acidic hardening and fixing solution.

The use of pyruvic aldehyde did not deteriorate the fog density and the other photographic properties of the thus obtained black and white negative image.

In the following table the melting point of the emulsion layer, obtained by the method of Example 1 as a standard showing the degree of hardening, is shown. Pyruvic aldehyde apparently results in a hardening action but the combined use of pyruvic aldehyde and formalin results in an unexpectedly greater hardening effect than would be expected when either of them is used without any increase of fog. Therefore, the physical damage or breaking of the surface layer could be reduced markedly even in the case of processing using an automatic de veloping machine with vigorous stirring.

Melting point of emulsion layer C.) 48.5 50.5 53.0 59.5

Hardener Used:

EXAMPLE 5 A monochromatic color photographic light-sensitive material, obtained by applying a gelatino-silver halide emulsion containing a magenta color former to a film base and then drying, was subjected to exposure and then to the following reversal color developing processing:

1 Uniform exposure of 8,0001uxes, sec. on emulsion surface.

Composition of the hardener Compositions C, D, E and F of Example 4 were used.

Composition of the first developer Gram N-methyl-p-aminophenol sulfate 2.0 Sodium sulfite 90.0 Hydroquinone 8.0 Sodium carbonate (monohydrate) 52.5 Potassium bromide 5.0 Potassium thiocyanate 1.0 Water to make 1,000 ml.

Composition of the second developer Benzyl alcohol ml 5.0 Sodium sulfite g 5.0 3-methyl-4-amino N ethyl-N-methanesulfonamide ethylaniline sulfate g 1.5 Potassium bromide g 1 Trisodium phosphate g 30 Ethylenediamine (70% aqueous solution) ml 7 Water to make 1,000 ml.

Composition of the bleaching solution Red prussiate g Sodium acetate a 40 Glacial acetic acid ml 20 Potassium bromide ..-g 30 Water to make 1,000 ml.

Composition of the fixing solution Sodium thiosulfate g 150 Sodium acetate g 70 Sodium sulfite 2 Potassium alum g 20 Water to make 1,000 ml.

Viewing the photographic characteristics of the thus obtained reversal color image, as shown in the following table, E and F of the invention are no worse than where no pyruvic aldehyde was added (C and D). With respect to the strength of the emulsion layer, moreover, the efiect of pyruvic aldehyde, in particular, multipled by the efiect of the coexistence of formaldehyde, is found, as shown by the reticulation point.

Reticu- Maxilation Senslmum point Hardener used tivity density 0.)

Not hardened 1. 80 2. 10 42 O 1. 75 2. 30 43 l. 80 2. 45 1. 80 2. 30 48 1. 80 2. 30 52 EXAMPLE 6 A solid reversal color photographic light-sensitive material containing a coupler in the light-sensitive emulsion layer was exposed and then subjected to processing similar to those of Example 5 but using a hardener of the following composition:

G H I .1

Sodium sulfate, g 2, 000 2, 000 2, 000 2, 000 Sodium acetate grams 20 20 20 Potassium iodide, milligrams- 20 20 20 20 Potassium bromide grams 23 23 23 23 Fonnalin 37%), milliliters 5 5 Pyruvic aldehyde (30%), milliliters 16 15 Water was added thereto to 1,000 ml. The pH at that time was 4.8.

The photographic characters of the sample processed with Hardener I were the same as those of the sample processed with Hardener G, whilst Hardener J gave the best results with respect to the strength of the emulsion layer.

Reticulation point of Hardener used: emulsion layer C.)

H 46 I 50 J 55 8 which process comprises contacting said emulsion layer With an aqueous silver halide developer solution containing pyruvic aldehyde hardener during a developing step in a photographic process.

3. The process as claimed in claim 2, wherein the amount of pyruvic aldehyde ranges from 1 g. to 20 g. per liter of the developer.

4. A process for the hardening treatment of a photographic element comprising a support having thereon an imagewise exposed gelatino silver halide emulsion layer which process comprises contacting said emulsion layer with an aqueous prehardener solution of pyruvic aldehyde and formaldehyde during a prehardening step in a photographic process.

5. The process as claimed in claim 4, wherein the amount of the pyruvic aldehyde ranges from 1 g. to 50 g. per liter of the prehardening solution.

6. The process as claimed in claim 4, wherein the amount of the formaldehyde as a 37% aqueous solution ranges from 5 cc. to 30 cc. per liter of the prehardening solution.

7. A prehardener composition comprising from 5 to 40 ml./l. of a 30% solution of pyruvic aldehyde, from 5 to 40 ml./l. of a 37% solution of formaldehyde, an inorganic salt to increase the ionic strength to greater than 1, and an acid or alkali to control the pH to from 3 to 1.2.

8. A prehardener composition comprising from 5 to 40 mL/l. of a 30% solution of pyruvic aldehyde, from 5 to 40 ml. of a 37% solution of formaldehyde, from 50 to 200 g./l. of sodium sulfate and an acid or alkali to adjust the pH to from 3 to 12.

9. The process as claimed in claim 1, wherein the amount of the pyruvic aldehyde ranges from 1 g. to 50 g. per liter of the prehardening solution.

10. A process for the hardening treatment of a photographic element comprising a support having thereon an imagwise exposed gelatino silver halide emulsion layer which process comprises contacting said emulsion layer with an aqueous silver halide developer solution containing pyruvic aldehyde and formaldehyde hardeners during a developing step in a photographic process.

11. A prehardener composition according to claim 7 wherein said pH is in the range of 4 to 11.

NORMAN G. TORCHIN, Primary Examiner W. H. LOUIE, JR., Assistant Examiner US. Cl. X.R. 

